The invention relates to a method for contact-free determination of quality features of a test subject of the meat goods class, particularly for the determination of the proportional fat/meat ratio of a half carcass. The test subject is illuminated and its image is scanned or detected by a video camera. The meat or fat tissue is discriminated according to the measure of the relative brightness of the corresponding tissue parts.
A method of this general type is known from U.S. Pat. No. 4,226,540, incorporated herein by reference. In this method, the real image of a sample scanned by a video camera is digitized relative to a threshold value for the discrimination of fat and meat. This threshold value corresponds to the mean brightness value between the brightest and darkest image locations. Although usable results have often been achieved with the known method, erroneous results cannot be excluded and are particularly produced by the following causes:
indistinct transitions from fat to meat and vice versa in a broad spectrum of gray scales of the real image;
differing colorations of different tissue types in meat, for example muscle tissue and connective tissue;
contaminations of the fatty cut surfaces, for example due to deficient draining of the blood when the carcass is split;
hemorrhages embedded in the loin fat which are caused by blows;
discolorations of skin areas when cooling the carcass;
camera instabilities with a tolerance range, for example in the aperture setting, displacement of the white sensitivity due to voltage decompensations and the like;
illumination instabilities; and
non-linear behavior of the image analysis in the computer.
The overall influence of these errors has led, in certain instances, to errors in the digitization, whereby particularly in the indistinct transitions from fat to meat, fat components were reproduced as meat or meat components were reproduced as fat.